Apparatus for measuring uniformity and/or dynamic-balance of tire

ABSTRACT

A measuring apparatus for the uniformity and/or the dynamic-balance of a tire is disclosed. The apparatus comprises a supporting member which is rotated with supporting a tested tire, a holding member which holds said supporting member with allowing to vibrate during rotation thereof and a regulating system which prevents the vibration of the supporting member during rotation thereof. The vibration of the supporting member is prevented by the regulating system for a uniformity measurement while it is allowed during a dynamic-balance measurement.

REFERENCE TO RELATED APPLICATIONS

This is a division of U.S. patent application Ser. No. 09/212,710 filedon Dec. 16,1998 now U.S. Pat. No. 6,131,455.

BACKGROUND OF THE INVENTION

The present invention relates to a tire uniformity and/ordynamic-balance measuring apparatus.

There have been known a tire uniformity measuring apparatus whichmeasures solely the uniformity of a tested tire and a tiredynamic-balance measuring apparatus which measures solely the dynamicbalance of a tested tire.

The uniformity measuring apparatus is constituted to rotate a tire bypressing a rotating drum against the outer circumferential surface ofthe tire and to measure the variation of loads in the radial directionand thrust direction. The uniformity measuring apparatus must beconstituted to be able to securely and firmly support the tested tire asthe load applied to the tested tire by the rotating drum amounts to 100kg or more.

On the other hand, the dynamic-balance measuring apparatus is to detectthe eccentricity of the tested tire based on the state of vibrationduring rotation thereof. Thus, the dynamic-balance measuring apparatusis to be so constituted as to support the tested tire to be rotatablewhile allowing it to vibrate during rotation thereof.

Due to the above-described difference in supporting the tested tire, ithas been unable to measure both the uniformity and the dynamic-balanceof the tested tire by a single common measuring apparatus, and at leasttwo independent apparatuses have been required for measuring both ofthem, which requires large space and expensive costs.

Furthermore, in the conventional tire uniformity measuring apparatus, atire mounting unit can mount only one type (width) of tire although thewidth differs depending upon the type of a tested tire. Accordingly, ithas been necessary to change a tire mounting unit depending upon thewidth of a tested tire, which is troublesome and cost-spending.

Moreover, in the conventional tire dynamic-balance measuring apparatus,it has been difficult to supply air to inflate a tested tire withoutdragging fine particles and the like therein during passing through theinside of the apparatus, which would affect on the results ofmeasurement.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide animproved apparatus capable of measuring the uniformity and/or thedynamic-balance of a tested tire therewith.

Another object of the present invention is to provide a measuringapparatus capable of carrying out a uniformity measurement withoutchanging a tire mounting unit despite the width of a tested tire.

Other object of the present invention is to provide a measuringapparatus capable of supplying air through inside of the apparatus toinflate a tested tire without dragging fine particles and the liketherein.

In one aspect of the present invention, there is provided a measuringapparatus for the uniformity and/or the dynamic-balance of a tire, whichcomprises: a supporting member which is rotated with supporting a testedtire; a holding member which holds the supporting member with allowingto vibrate during rotation thereof; and a regulating system whichprevents the vibration of the supporting member during rotation thereof,and wherein the vibration of the supporting member is prevented by theregulating system during a uniformity measurement.

With thus constituted measuring apparatus, the spindle holding a testedtire can vibrate during rotation thereof for the dynamic-balancemeasurement, while the vibration of the spindle e is prevented duringrotation thereof for the uniformity measurement, which enables tomeasure both the dynamic-balance and the uniformity of a tested tire bya single apparatus.

When the uniformity measurement is carried out, a rotary drum is pressedagainst the circumferential surface of the tested tire

In the embodiment, the holding member comprises a housing whichrotatably holds the supporting member, and a plurality of elasticmembers provided between the housing and a frame member for supportingthe housing.

Further, the regulating system comprises a coupling member supported bythe frame member to be movable between operative and inoperativepositions, and the coupling member firmly couples the housing to theframe member at the operative position when the coupling member is movedto the operative position during a uniformity measurement.

The regulating system may further comprise a rotatable shaft membersupported by the frame member and disposed on the extension of therotary axis of the supporting member, and a chuck mechanism provided atone end of said rotatable shaft member for chucking the supportingmember at the side opposite to the holding member across the tire. Thechuck mechanism chucks the supporting member during a uniformitymeasurement sa as to connect the supporting member to the rotatableshaft member.

Moreover, the supporting member comprises a rotatable spindle having afirst rim and an axially extending hollow portion, a locking shafthaving a second rim and inserted into the hollow portion of the spindleso that the tested tire is pinched between the first and second rims,and a locking system which firmly locks the locking shaft to therotatable spindle. The axial distance between the first and second rimsis changed by shifting the position of the locking shaft relative to therotatable spindle to be locked by the locking system.

The locking system may comprise a plurality of engaging steps formed onthe outer circumferential surface of the locking shaft and arranged inthe axial direction thereof, and at least one lock member provided onthe spindle to be movable in the direction perpendicular to the axialdirection of the spindle. The lock member is provided with engagingsteps to be meshed with the engaging steps of the locking shaft to lockthe locking shaft to the spindle when the lock member is moved to abutagainst the locking shaft.

Optionally, a plurarity of lock members may be provided and arrangedradially at the interval of a predetermined angle about the axis of thespindle.

Furthermore, an air passage system is provided in the spindle forsupplying air into the tire held between the first and second rims, andis formed to be isolated from the portion of the spindle where the lockshaft is to be inserted and from the locking system. The air passage maybe formed to pass the intervals among a plurarity of lock members.

In another aspect of the present invention, there is provided ameasuring apparatus for the uniformity of a tire, which comprises arotatable spindle having a first rim and an axially extending hollowportion, a locking shaft having a second rim and inserted into thehollow portion of the spindle so that the tested tire is pinched betweenthe first and second rims, a locking system which firmly locks thelocking shaft to the rotatable spindle, the axial distance between thefirst and second rims being changed by shifting the position of thelocking shaft relative to the rotatable spindle to be locked by saidlocking system, and a rotary drum arranged to be pressed against thecircumferential surface of the tested tire.

With thus constituting, it becomes unnecessary to change a tire mountingunit, as required in the conventional one, depending upon the width of atested tire for a uniformity measurement.

The locking system may comprise a plurality of engaging steps formed onthe outer circumferential surface of the locking shaft and arranged inthe axial direction thereof, and at least one lock member provided onthe spindle to be movable in the direction perpendicular to the axialdirection of the spindle, the lock member being provided with engagingsteps to be meshed with the engaging steps of the locking shaft to lockthe locking shaft to the spindle when the lock member is moved to abutagainst the locking shaft.

Optionally, a plurarity of lock members may be provided and arrangedradially at the interval of a predetermined angle about the axis of thespindle.

In other aspect of the present invention, there is provided a measuringapparatus for the dynamic-balance of a tire, which comprises a rotatablespindle having a first rim and an axially extending hollow portion, alocking shaft having a second rim and inserted into the hollow portionof the spindle so that the tested tire is pinched between the first andsecond rims, a locking system which firmly locks the locking shaft tothe rotatable spindle, the axial distance between the first and secondrims being changed by shifting the position of the locking shaftrelative to the rotatable spindle to be locked by the locking system,and an air passage system provided in the spindle for supplying air intothe tire held between the first and second rims, and is formed to beisolated from the portion of the spindle where the lock shaft is to beinserted and from the locking system.

With thus constituting, it can be prevented for air supplied to inflatea tested tire to drag fine particles and the like therein during passingthrough inside of the apparatus.

The locking system may comprise a plurality of engaging steps formed onthe outer circumferential surface of the locking shaft and arranged inthe axial direction thereof, and a plurarity of lock members areprovided and arranged radially at the interval of a predetermined angleabout the axis of the spindle, each of the lock members being movable inthe direction perpendicular to the axial direction of the spindle, andbeing provided with engaging steps to be meshed with the engaging stepsof the locking shaft to lock the locking shaft to the spindle when thelock member is moved to abut against the locking shaft, and wherein theair passage system is formed to pass the intervals among the plurarityof lock members.

DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1 is a front view of a compound measuring apparatus embodying theinvention;

FIG. 2 is a plan view of the measuring apparatus shown in FIG. 1;

FIG. 3 is a side sectional view of a spindle e unit portion of themeasuring apparatus shown in FIG. 1;

FIG. 4 is an enlarged view of a bracket area of the spindle unit portionshown in FIG. 3;

FIG. 5 is a sectional view taken along the line B-B′ in FIG. 4 forillustrating a bracket structure;

FIG. 6 is a sectional view taken along the line C-C′ in FIG. 5 forillustrating an air passage structure;

FIG. 7 is a side sectional view of an inserter unit portion of themeasuring apparatus shown in FIG. 1; and

FIG. 8 is a sectional view taken along the line A-A′ in FIG. 1 forillustrating a spindle support structure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A measuring apparatus for uniformity and/or dynamic-balance of a tire,which embodies the present invention, will be described hereinafter withreference to the accompanying drawings.

FIGS. 1 and 2 are a front and a plan views, respectively, showing thebasic constitution of a measuring apparatus 1. In the followingdescription, the “up” and “down” are defined as indicated in FIG. 1. Itshould be noted, however, the measuring apparatus 1 may be verticallyinversely constituted or horizontally arranged instead of the disclosedone.

The frame of the measuring apparatus 1 comprises a base 50, struts 52extending upward from the base 50, and a roof 54 supported by the struts52. A spindle 100 is mounted on the base 50 to hold and rotate a testedtire T.

First, a tested tire supporting system will be described by referring toFIG. 3. FIG. 3 is a side sectional view of the spindle portion of theapparatus shown in FIG. 1. A tested tire T is sandwiched and heldbetween a pair of rims 10 and 20, which will be described later.

The spindle 100 is, as shown in FIG. 3, constituted by a hollow spindleshaft 120, a bracket 150, and a hollow shaft 170, which are verticallyand coaxially connected in this order.

The spindle shaft 120 is rotatably supported by a spindle housing 110via bearings 112. The spindle housing 110 is mounted on the base 50 (seeFIG. 1) via four horizontal bar springs 102.

The lower rim 10 is attached to the upper end of the hollow shaft 170 ofthe spindle 100. By inserting a lock shaft 300 with the upper rim 20fixed thereto, into the bracket 150 through the hollow shaft 170, thetire T can be sandwiched and held between the lower and upper rims 10and 20 as illustrated in FIG. 3.

A pulley 140 for rotationally driving the spindle shaft 120 is mountedat the lower end of the spindle shaft 120. An endless belt 142 is passedaround the pulley 140 so that the pulley 142 is rotationally driven viathe endless belt 142 by a spindle driving motor 130 which is fixed tothe base 50. That is, when the spindle driving motor 130 is driven, thespindle 100 is rotated with the tire T held between the lower and upperrims 10 and 20.

FIG. 4 is a side sectional view of the bracket 150 into which the lockshaft 300 is inserted. FIG. 5 is a sectional view taken along the lineB-B′ of FIG. 4 (the lock shaft is omitted). At the outer periphery ofthe lower part of the lock shaft 300, fifteen-step lock grooves 302 arearranged vertically. The bracket 150 is provided with lock members 160opposed to the outer peripheral surface of the lock shaft 300. Each lockmember 160 has six-step lock claws 162 arranged vertically, and theselock claws 162 engage with the lock grooves 302 of the lock shaft 300.

As shown in FIG. 5, four lock members 160 are provided radially withrespect to the center of the bracket 150 at intervals of 90°, and thelock claws 162 of each of the lock members 160 project into a lock shaftinsertion portion 155 in which the lock shaft 300 is to be inserted. Thelock members 160 are slidably held in four sliding grooves 151 formed inthe bracket 150 so as to be capable of moving in the directions toengage with and to be released from the lock shaft 300.

A locking cylinder 165 for driving each lock member 160 is mounted tothe outer peripheral end of the bracket 150 via a holding member 152.The lock member 160 is secured to the tip end portion of a plunger 166of the locking cylinder 165. The plunger 166 is urged in the directionto be away from the lock shaft 300 by a spring 168. That is, t he lockmember 160 is urged in the direction to be disengaged from the lockshaft 300 .

The air for driving the locking cylinder 165 is supplied through an airpassage branching from a later-described air supply system. When thelocking cylinder 165 is made operative, the lock claws 162 of thelocking member 160 engage with the lock grooves 302 of the lock shaft300, and when the locking cylinder 165 is made inoperative, the lockmember 160 is moved so that the lock claws 162 are disengaged from thelock grooves 302.

As above constituted, by inserting the lock shaft 300 into the bracket150 of the spindle 100 through the hollow shaft 170, and making thelocking cylinders 165 operative, the tire T can be surely retainedbetween the lower rim 10 and the upper rim 20. On the contrary, bymaking the locking cylinder 160 inoperative, the lock shaft 300 becomesfree and can be pulled out of the spindle 100, thereby the tire T isable to be removed from between the lower rim 10 and the upper rim 20.

As shown in FIGS. 4 and 5, the bracket 150 is provided with pins 154,respective one of which is arranged to be vertically moved following thehorizontal movement of the corresponding lock member 160. That is, thepin 154 is spring-biased to protrude above the surface along which thelock member 160 slides, and is pressed against a concave portion 164formed at the bottom surface of the lock member 160. Upon horizontalmovement of the lock member 160, the pin 154 is guided up and down inaccordance with the configuration of the concave portion 164. Thus, bydetecting the vertical position of a disk 156 which is fixed to thelower end of the pin 154 by means of a positional sensor (not shown), itcan be discriminated whether the lock member 160 is at the lock positionwhere the lock member 160 engages with the lock shaft 300 or at therelease position where the lock member 160 is separated/disengaged fromthe lock shaft 300.

Hereafter, air supply system for blowing air into the tire T heldbetween the rim 10 and the rim 20 will be described.

As shown in FIG. 2, the spindle shaft 120 is a hollow shaft member, andwithin its hollow portion 115, there is provided an air pipe 119 foraxially extending through the hollow portion 115. The upper end portionof the air pipe 119 is fixed to the upper end of the spindle shaft 120through a flange 116. Into the hollow portion 115 and the air pipe 119,air is fed from a rotary joint 145 provided at the lower end of thespindle shaft 120. An air hose 132 for supplying air from an air source(not shown) is connected to the rotary joint 145.

The interior of the hollow portion 115 (i.e., outside of the air pipe119) is used as an air passage for carrying air which inflates the tireT, and the inside of the air pipe 119 is used as an air passage forcarrying air for driving the locking cylinder 165.

FIG. 6 is a sectional view taken along the line C-C′ in FIG. 5 forillustrating an air passage structure. As shown in FIG. 6, the air fedfrom the rotary joint 145 through the outside of the air pipe 119 passesthrough slit portion 116 a formed in the flange 116, and reaches acavity 118 formed at the bottom of the bracket 150. This cavity 118 isconnected to first air passages 158.

As seen from FIGS. 5 and 6, four of the first air passages 158 areformed in the bracket 150. The first air passages 158 are arrangedradially with respect to the axis of the bracket 150 at intervals of90°, and provided at positions not interfering with any of the slidinggrooves 151, the lock members 160 and the locking cylinders 165.

The first air passages 158 axially extend in the bracket 150. The hollowshaft 170 located above the bracket 150 is formed with second airpassages 172 coupled to the first air passages 158. The second airpassages 172 axially extends in the hollow shaft 170.

Therefore, the air fed from the rotary joint 145 to the first airpassages 158 in the bracket 150 through the interior of the hollowportion 115 (outside of the air pipe 119) passes through the air passage172 in the hollow shaft 170 and supplied to the interior of the tire Tsandwiched between the rims 10 and 20.

The air fed from the rotary joint 145 through the air pipe 119 reaches acavity 117 formed in the bracket 150. The air passes throughcommunicating holes 1171 a (formed at positions where they do notinterfere with the first air passages 158) extending from the cavity 117to the outer peripheral surface of the bracket 150. At the outlet ofrespective communicating hole 117, provided are a joint and an air pipe(both are not shown), from which the air is supplied to the lockingcylinder 165 (FIG. 4).

In this embodiment, as the air passages 158 are disposed at thepositions where they do not interfere with the lock members 160, thesliding grooves 151, and other elements, the air passages 158 can beisolated from an environment where fine particles are easily produced.Thereby, it can be prevented for fine particles and the like to enterinto the air blown into the tire T.

Hereafter a lock shaft holding and elevating system will be described.

FIG. 7 is a side sectional view of an inserter unit portion of theapparatus shown in FIG. 1. As shown in FIG. 7, a mounting member 310 formounting the upper rim 20 onto the lock s haft 300 is provided with afixing ring 320 engaged with later-described chuck claws 222 from theinside.

As shown in FIG. 3, a n inserter unit 200 for inserting (or pulling out)the lock shaft 300 into (from) the spindle 100 by axially elevating thelock shaft 300 is installed in an elevating housing 60 disposed abovethe roof 54 shown in FIG. 1. The elevating housing 60 is supported so asto be movable vertically by four sets of linear guides 61 and carriages62 (only one set is shown in FIG. 1), and is driven vertically by a pairof elevating cylinders 65.

As shown in FIG. 7, the inserter unit 200 has an intermediate shaft 240rotatably supported to follow the rotation of the spindle 100. Theintermediate shaft 240 is attached to a rotating shaft 250 rotatablysupported by the elevating housing 60 via bearings 255.

Chuck claws 222 internally engaging the fixing ring 320 of the lockshaft 300 are provided at the lower end of the intermediate shaft 240.The chuck claws 222 are urged inward by spring members 224. Theintermediate shaft 240 vertically movably holds a chuck driving member230 having a conical tip that abuts on the tapered surfaces of the chuckclaws 222 from above.

The chuck driving member 230 is vertically driven by air pressure. Acavity 242 is formed inside the intermediate shaft 240, and has adiaphragm 235 fixed to the upper end of the chuck driving member 230. Anair pipe 262 penetrates the hollow portions inside the rotating shaft250 and intermediate shaft 240 to supply air to the cavity 242. A rotaryjoint 260 for supplying air to the air pipe 262 is provided at the upperend of the rotating shaft 250, and has connected thereto an air hose 266coupled to an air supply source (not shown).

With this constitution, when air is supplied from the rotary joint 260to increase the internal pressure, the chuck driving member 230 lowers.This operation causes the chuck claws 222 to move outward against thebiasing force of the spring members 224 to engage the fixing ring 32. Onthe other hand, when air is discharged from the rotary joint 260 toreduce the internal pressure of the cavity 242, the chuck driving member230 elevates. This operation causes the chuck claws 222 to move inwarddue to the biasing force of the spring members 224 to release the fixingring 320 from locking effected by the chuck claws 222. FIG. 7 shows bothstates in which the chuck claws 222 lock the fixing ring 320 (on theleft half side), and in which locking is released (on the right halfside).

Thus, when air is supplied from the rotary joint 260, the chuck claws222 chuck the fixing ring 320 of the lock shaft 300 (inserted into thespindle 100). When the spindle 100 is then rotated, the rotating shaft250 and intermediate shaft 240 follow this rotation.

As shown in FIG. 1, step-like regulating members 70 for regulating thevertical position of the lock shaft 300 are provided on the roof 54. Theregulating member 70 is constituted to slide on a guide rail 71 disposedon the roof 54, and is moved along the rail 71 by a ball springmechanism 74 driven by a motor 72 via a belt 73. The elevating housing60 includes elevating stoppers 68 (FIG. 2), each of which abuts on thestep portion of the regulating member 70 from above.

The measuring apparatus 1 constituted as described above holds the tireT as described below.

First, air is supplied from the rotary joint 260 to cause the chuckclaws 222 to chuck the lock shaft 300, and the elevating cylinder 65 isdriven to elevate the elevating housing 60 in order to pull the lockshaft 300 out of the spindle 100. Then, the tire T is set on the lowerrim 10, and the motor 72 is driven to move the regulating members 70 toappropriate positions. The elevating cylinders 65 are driven again tolower the elevating housing 60 until the elevating stoppers 68 abut onthe regulating members 70. When the elevating stoppers 68 abut on theregulating members 70, the lock cylinders 165 are turned on to engagethe lock members 160 with the lock shaft 300 again.

When six locking pawls 162 of the locking member 160 engage a portion upto the sixth stage counted from the top stage of 15-stage locking flutes302 of the locking shaft 300 as shown in FIG. 3, the width of a tirepinched between the upper rim 20 and the lower rim 10 is the minimumvalue W1. In contrast, when six locking pawls 162 of the locking member160 engage a portion up to the sixth stage counted from the bottom stageof the locking flutes 302 of the locking shaft 300 as shown in FIG. 7,the width of the tire pinched between the upper rim 20 and the lower rim10 is the maximum value W2.

By selecting which locking flutes 302 of the locking shaft 300 thelocking pawls 162 of the locking member 160 engage in this way, it ispossible to cope with a plurality of widths (nine widths in thisembodiment) of tires between the minimum width W1 and the maximum widthW2.

FIG. 8 is a sectional view taken along the line A-A′ in FIG. 1 forillustrating a spindle support structure.

As shown in FIGS. 1 and 8, the spindle housing 110 is mounted on thebase 50 via bar springs 102 extending in the horizontal direction and issupported by bar members 104 suspended from the base 50 in the verticaldirection. The bar springs 102 can be elastically deformed in thedeflecting direction shown as “W” in the FIG. 8, and the spindle housing110 can vibrate in the direction referred to as “X” in FIG. 8, within asurface crossing the central axis of the spindle 100.

In order to detect vibration in the X direction occurring when thespindle 100 is rotated with the tire T mounted, a mounting bar 180extending perpendicularly to both the X direction and the axialdirection of the spindle 100 is attached to the spindle housing 110. Inaddition, a mounting bar 182 extends from the base 50 and opposite tothe mounting bar 180. A load cell 185 that detects the load effected inthe X direction is sandwiched between the two mounting bars 180 and 182.

During a uniformity measurement, as a large load is effected on thespindle shaft 120, the spindle housing 110 must be prevented fromvibrating. Thus, as shown in FIG. 8, pressing members 192 each having aconical tip are provided on the base 50, and a pair of tapered recessedportions 194, each of which receives the pressing member 192, are formedon the spindle housing 110. The pressing member 192 is driven by avibration regulating cylinder 190.

That is, during a uniformity measurement, the vibration regulatingcylinder 190 is turned on to press the pressing member 192 against therecessed portion 194 in order to prevent the spindle housing 110 fromvibrating. On the other hand, during a dynamic-balance measurement, thevibration regulating cylinder 190 is turned off to release the pressingmember 192 from the recessed portion 194 in order to allow the spindlehousing 110 to vibrate in the X direction.

In addition, during a uniformity measurement, as shown in FIG. 7, thechuck claws 222 engage the fixing ring 320 of the lock shaft 300. Thatis, the top and bottom (the spindle 100 side and inserter unit 200 side,respectively) of the tire are firmly held so that the tire T canwithstand the load effected when the rotating drum 30 is pressed againstit. On the other hand, during a dynamic-balance measurement, chuckingexecuted by the chuck claws 222 is released to allow the spindle housing110 to vibrate in the X direction.

In order to conduct a dynamic-balance measurement, air is supplied tothe inside of the tire T held between the lower and upper rims 10 and 20to inflate it and then rotates the spindle 100 to detect a variation inload effected on the load cell 185 during the rotation of the spindle100. The method for calculating dynamic balance based on the detectedvariation of the load is well known, so its description is omitted. Themeasuring apparatus 1 calculates which portion of the tire T a balanceweight is to be placed, based on the result of the calculation ofdynamic balance, and uses a marking device (not shown) to mark thisportion.

The uniformity measurement uses a rotating drum 30 (see FIGS. 1 and 2).The rotating drum 30 is mounted in a movable housing 32 that can slideon rails 31 extending in a direction in which the drum 30 approaches andleaves away from the tire T, and is moved by a rack pinion mechanism 35(a pinion 36 and a rack 38) that is driven by a motor 34 (FIG. 2). Inaddition, load cells 33 are attached to a rotating shaft of the rotatingdrum 30 to detect a reaction force applied in the radial direction andthrust direction by the tire T to the rotating drum 30.

During a uniformity measurement, the control section (not shown) of themeasuring apparatus 1 drives the motor 34 to press the rotating drum 30against the tire T. Then, a variation in load effected on the load cell33 is detected during the rotation of the spindle 100.

As above, the measuring apparatus 1 according to this embodiment enablesa single apparatus to measure both uniformity and dynamic balance of atested tire.

The present disclosure relates to subject matters contained in JapanesePatent Applications No. HEI 9-363399 filed on Dec. 16, 1997, No. HEI10-39632 filed on Feb. 5, 1998 and No. HEI 10-39633 filed on Feb. 5,1988, which are expressly incorporated herein by reference in theirentireties.

What is claimed is:
 1. A structure for rotatably supporting a tire,which comprises: a frame member; a spindle unit consisted by a spindleshaft, a bracket and a hollow shaft vertically and coaxially connectedin this order; said spindle shaft being rotatably supported by saidframe member; said hollow shaft having a lower rim at the upper endthereof and an axially extending hollow portion; said bracket having anaxially extending lock shaft insertion portion to be continued from saidhollow portion of the hollow shaft; a lock shaft having an upper rim atthe upper end thereof, said lock shaft being inserted into said hollowportion and said lock shaft insertion portion so that a tire is pinchedbetween said upper and lower rims, said lock shaft being formed with aplurality of lock grooves on the outer peripheral surface of the lowerportion thereof; and a plurality of lock members provided in saidbracket and arranged radially about the axis of said spindle unit, eachof said lock members being slidable in the direction perpendicular tothe axial direction of said spindle unit toward and away from the axisof said spindle unit, a plurally-stepped lock claw being formed on eachof said lock members to be engaged with said lock grooves of the lockshaft so as to lock said lock shaft with respect to the spindle unitwhen the lock member is slid toward the axis of said spindle unit,wherein the axial distance between said upper and lower rims is changeddepending upon the relative position of said lock shaft with respect tosaid spindle unit at the time when said lock shaft is locked to saidspindle unit by means of said lock members.
 2. The supporting structureaccording to claim 1, which further comprises: an axially extendinghollow portion formed in said spindle shaft; an air pipe installed insaid hollow portion of the spindle unit, the remaining interior of saidhollow portion of the spindle shaft being defined as another separatedair passage; a plurality of axially extending air passages formed insaid bracket between each adjacent pair of said locking members, saidair passages being connected to said another air passage of the hollowportion; and a plurality of axially extending air passages formed insaid hollow shaft to be continued from said plurality of air passages ofsaid bracket, the upper ends of said air passages of the hollow shaftbeing open to spacing to be defined by said upper and lower rims as wellas the tire pinched between said rims, said another air passage of thespindle shaft, said air passages of the bracket and said air passages ofthe hollow shaft constituting an air supply passage for inflating thetire pinched between said rims.
 3. The supporting structure according toclaim 2, wherein each of said lock members is driven to slide by meansof an air cylinder connected thereto, and wherein said air pipe in saidspindle shaft is connected to respective air cylinders to supply airthereto.
 4. The supporting structure according to claim 1, which furthercomprises: a rotatable shaft member disposed on the extension of therotary axis of said spindle unit; a chuck mechanism provided at thelower end of said rotatable shaft member for chucking said lock shaft atthe upper side thereof; and a supporting system which supports saidrotatable shaft member, said supporting system elevating said rotatableshaft in case said lock shaft is to be pulled out of said spindle unitfor mounting and/or releasing a tire on and from the apparatus.
 5. Astructure for rotatably supporting a tire, which comprises: a framemember; a spindle unit having a bracket and a connected axiallyextending hollow portion; said spindle unit rotatably supported by saidframe member; said hollow portion having a lower rim; a lock shafthaving an upper rim, said lock shaft being inserted into said hollowportion so that a tire is pinched between said upper and lower rims,said lock shaft being formed with a plurality of lock grooves on theouter peripheral surface of the lower portion thereof; and a pluralityof lock members provided in said bracket and arranged radially about theaxis of said spindle unit, each of said lock members being slidable inthe direction perpendicular to the axial direction of said spindle unittoward and away from the axis of said spindle unit, a plurally-steppedlock claw being formed on each of said lock members to be engaged withsaid lock grooves of the lock shaft so as to lock said lock shaft withrespect to the spindle unit when the lock member is slid toward the axisof said spindle unit; wherein the axial distance between said upper andlower rims is changed depending upon the relative position of said lockshaft with respect to said spindle unit at the time when said lock shaftis locked to said spindle unit by means of said lock members.
 6. Thesupporting structure according to claim 5, which further comprises: anair pipe installed in said hollow portion of the spindle unit, theremaining interior of said hollow portion of the spindle unit beingdefined as another separated air passage; a plurality of axiallyextending air passages formed in said bracket between each adjacent pairof said locking members, said air passages being connected to saidanother air passage of the hollow portion; and a plurality of axiallyextending air passages formed in said hollow portion to be continuedfrom said plurality of air passages of said bracket, the upper end ofsaid air passages of the hollow portion being open to spacing defined bysaid upper and lower rims as well as the tire pinched between said rims;said another air passage of the spindle unit, said air passages of thebracket and said air passages of the hollow portion constituting an airsupply passage for inflating the tire pinched between said rims.
 7. Thesupporting structure according to claim 6, wherein each of said lockmembers is driven to slide by means of an air cylinder connectedthereto, and wherein said air pipe in said spindle unit is connected torespective air cylinders to supply air thereto.
 8. The supportingstructure according to claim 5, which further comprises: a rotatableshaft member disposed on the extension of the rotary axis of saidspindle unit; a chuck mechanism provided at the lower end of saidrotatable shaft member for chucking said lock shaft at the upper sidethereof; and a supporting system which supports said rotatable shaftmember in case said lock shaft is to be pulled out of said spindle unitfor mounting and/or releasing a tire on and from the apparatus.